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Bioswale at the SPICE Home shopping centre parking lot
Published on 05 May 2020
Latvia
This is the good practice's implementation level. It can be national, regional or local.
About this good practice
The conventional collection and conveyance of stormwater runoff was not possible due to the limited capacity of the current urban drainage system. In the green part of the development plot, downstream from the parking lot, a bioswale was constructed. It offers multiple functions: stormwater runoff attenuation before restricted discharge into sewer network, groundwater recharge, stormwater treatment by plants and soil, landscaping function, space for snow storage during winter.
The bioswale is located at the side of the parking lot, from which stormwater is conveyed via surface runoff (sheet flow). The stormwater enters the bioswale via openings in the curbstones. The bioswale is implemented as an artificial depression with depth up to 50cm, filled with structured soil designed to provide better water treatment as well as a mix of plants tolerant to short periods of flooding. Most of the accumulated stormwater is treated by the plants and soil and infiltrates. In the event of extreme rain, an overflow with a limited discharge of at most 5 l/s is provided to the municipal stormwater sewer.
The main stakeholders are both the shopping centre/owner and the municipality. As this is a new practice, that contradicts some conventional rules, the municipality had to find the way to allow building this good practice by flexible interpretation of the building code. Also, this practice noted a necessity to amend the local regulation in order to facilitate more of such green features.
The bioswale is located at the side of the parking lot, from which stormwater is conveyed via surface runoff (sheet flow). The stormwater enters the bioswale via openings in the curbstones. The bioswale is implemented as an artificial depression with depth up to 50cm, filled with structured soil designed to provide better water treatment as well as a mix of plants tolerant to short periods of flooding. Most of the accumulated stormwater is treated by the plants and soil and infiltrates. In the event of extreme rain, an overflow with a limited discharge of at most 5 l/s is provided to the municipal stormwater sewer.
The main stakeholders are both the shopping centre/owner and the municipality. As this is a new practice, that contradicts some conventional rules, the municipality had to find the way to allow building this good practice by flexible interpretation of the building code. Also, this practice noted a necessity to amend the local regulation in order to facilitate more of such green features.
Resources needed
Total construction cost is approximately 50 thousand EUR. The design took 3 months, construction of the bioswale (as a part of the wider development) – 6 months. This project has been managed by one project manager and an assistant, who managed this project as part of their day-to-day activities.
Evidence of success
The bioswale is the first green infrastructure of such size and function in Riga. It performs well in different seasons and proved itself even in extreme weather events. The vegetation is strong and maintenance is relatively easy and not demanding. Also, municipal sewer compared to conventional projects is drastically reduced. Furthermore, public and expert communities are important stakeholders as the site is a popular showcase of green-blue infrastructure in Latvia and Baltic countries.
Potential for learning or transfer
This practice has seen a lot of attention already from specialists and municipalities in Latvia, Russia, Lithuania, Estonia, Netherlands, and other countries. It is a good example of a cost-effective and multi-functional solution.
Good practice owner
You can contact the good practice owner below for more detailed information.
Organisation
Ltd Kapitel, Duntes street 3, Rīga, LV-1013, www.kapitel.lv
Latvia
Latvija
Contact
Project managers